CHEMISTRY COMMUNITY

Peter Fernandez 2K

To classify if a salt is basic or acidic, you need to separate the compound into its individual ions. Once you do that, you need to determine if the ion came from a weak/strong acid/base. For example, NH4+ is the conjugate acid of the weak base NH3. Therefore, the NH4+ ion is likely to donate its H+...

Peter Fernandez 2K

First, take the -log[OH-] to find the pOH of the solution. Then subtract 14-pOH to get pH. Finally, solve for [H+] by doing 10^-pH.

Peter Fernandez 2K

It'll remain charged. When the pH is higher than the pKa, the deprotonated version of the acid will become more dominant in the solution.

Peter Fernandez 2K

A molecule is polydentate if it has more than one atom that can donate a lone pair to the transition metal. For 9C.5a, you can see in the molecular formula NH(CH2CH2NH2)2 that there are 3 nitrogen atoms that will all have a lone pair to donate, hence it is tridentate. For CO32- in part B, while it d...

Peter Fernandez 2K

When one of the compounds in the coordination compound already has a Greek prefix, like ethylenediamine, you'd use bis- and other prefixes of the sort.

Peter Fernandez 2K

To find the oxidation state of the metal, you look at the total charge of the coordination compound and the charge of the anions in the compound. Since there are 4 Cl- and the total charge is -1 for the compound, Al must have an oxidation state of +3 to get the -1 charge.

Peter Fernandez 2K

Based on the rules for naming, the anion outside of the coordination compound does not need the Greek prefix.

Peter Fernandez 2K

Since there are 2 Cl- anions, the total charge of the coordination compound must also equal -2. Since there is 1 Cl- in the coordination compound, the only way for ot to end up being +2 charged is if the Co has a charge of +3.

Peter Fernandez 2K

A delocalized pi bond is the term used when a molecule forms resonance structures. Since double bond placements in resonance structures can vary between them, it is said that the electrons are delocalized as they are not in one set position like in CO2 where the pi bonds are in a set position.

Peter Fernandez 2K

I2 has many more polarizable electrons than Cl2 which means that the London Dispersion Forces between I2 molecules are stronger and require more energy to separate.

Peter Fernandez 2K

Generally, polarizability will increase as the number of electrons in an atom increase as they will be held less and less tightly by the nucleus and therefore have an increased chance of being polarized.

Peter Fernandez 2K

For the Lewis structure of HOCO, why does the carbon have the radical?

Peter Fernandez 2K

Elements starting after and including Phosphorus have access to their d-orbitals which extra electrons can occupy!

Peter Fernandez 2K

A is the central atom and there is only one of it, so yes it'll never have a subscript. Only the things bonded to it (either the X's or E's) will.

Peter Fernandez 2K

I struggled with this too. However, in the feedback it also said one of the structures is cyclic. This means that the carbons would form a triangle. Then you would be able to figure out where to place double bond and the four hydrogens to fulfill the octet rule :)

Peter Fernandez 2K

Since AsO4^3- has all 4 oxygens bonded to the central As and the central As has no lone pairs, it forms a tetrahedral shape and since all 4 of the bonded atoms are the same, it is symmetric and the dipoles cancel out, leaving it to be nonpolar.

Peter Fernandez 2K

A coordination bond is a covalent bond in which one atom (the Lewis base) donates both of its electrons to an electron acceptor (the Lewis acid) to form the bond. In a regular covalent bond, the two atoms each share one of their own electrons.

Peter Fernandez 2K

If there is more than one bond between two atoms, one of them will be a sigma and one will be a pi (if it's a double bond) or two will be pi bonds (if it's a triple bond). A delocalized pi bond occurs when the molecule forms resonance structures. In resonance, since the double/triple bonds can be pl...

Peter Fernandez 2K

CCl4 is non-polar, it makes a tetrahedral shape with all of the dipoles cancelling each other out. SF4 is polar since it's a see-saw shape which is asymmetrical and the dipoles do not cancel out.

Peter Fernandez 2K

We use the trends in atomic radius to determine bond length. Since atomic radius increases down a group, P has the greater atomic radius which means a longer bond is needed between the P and the F atoms.

Peter Fernandez 2K

When comparing CHI3 and CHF3, it's more important to look at the size and the polarizability of the electrons when determining boiling points. Yes, fluorine does have a higher electronegativity but iodine has more polarizable electrons since the effective nuclear charge is not as strong, which means...

Peter Fernandez 2K

The favorable resonance structure is the one that has 0 formal charge on every atom (or as close to zero) and also follows the octet rule (unless the atom can form more than an octet).

Peter Fernandez 2K

Cations that are smaller in radius in particular have the highest polarizing power while larger anions are more polarizable.

Peter Fernandez 2K

The question is essentially asking to find the most stable structure based on the formal charges. You always want to find the structure that has 0 formal charge on every atom (or as close to that as possible) and if each element satisfies the octet rule (unless it is an atom that can form higher tha...

Peter Fernandez 2K

Determining polarity can be first determined by the difference in electronegativities of the two atoms. Generally, the only true nonpolar molecules occur between molecules of the same atom. By looking at the periodic table, the distance between the two atoms between each other will generally tell yo...

Peter Fernandez 2K

Induced dipole-induced dipole forces will be present in any molecule regardless of polarity. This is because of the constant motion of electrons. At some point, a majority of the electrons in one of the bonded atoms will be clustered in one area and end up inducing a dipole in the other atom.

Peter Fernandez 2K

My TA in discussion section said that the next midterm will not cumulative, only the final.

Peter Fernandez 2K

do most ionic bonds have covalent character? Yes, Professor Lavelle said in lecture that all ionic bonds must have some covalent character because cations will exert electrostatic attraction on the electrons of the anion. Depending on the size and number of electrons the anion has, the electrons wi...

Peter Fernandez 2K

In all covalent bonds, whether it is polar or nonpolar, the movement of electrons means that at some point, there will be a time where the electrons are bundled up more in one place rather than the other. This creates a temporary, very weak dipole moment where the atom has a partial negative charge.

Peter Fernandez 2K

A Lewis-acid is something like a metal cation with a positive charge, a molecule deficient in electrons or a molecule with polar double covalent bonds, while a Lewis-base is something with a lone pair of electrons or an anion.

Peter Fernandez 2K

When it says "overwhelmingly" I take that to mean that the bonds in the molecule are basically equal to the given bonds. If it says ample, they're not equal to the length of the bonds they gave. For example, it says the C-O bond in the molecule is 128pm. It is given that C-O single bond is...

Peter Fernandez 2K

Since you added a double bond between N and C, you can find the charge using the FC equation. Since N has 5 valence electrons, 4 bonds but no lone pairs, 5-4= +1 charge on the N.

Peter Fernandez 2K

Lewis-acids are those that a accept lone pairs (so metal cations, molecules with electron deficient atoms and polar double bonds), while lewis-bases are those that have an excess of e- (anions or those with lone pairs)

Peter Fernandez 2K

I just searched them up. In high school when we memorized polyatomic ions, I just remembered that the -ite suffix means that it has less oxygens. So for example, I just always knew nitrate was NO3-, so I could figure out nitrite was no2-.

Peter Fernandez 2K

Going down a group, radius increases. Going left to right, radius decreases.

Peter Fernandez 2K

It does! Because of the fact that when the electron is in the 2s orbital, it is closer to the nucleus and is thus more attracted. However, if it is in the 2p orbital, it is farther away and therefore experiences less attractive forces.

Peter Fernandez 2K

It would be 2 sig figs since zeros on the left of the number wouldn't count but the zeros to the right would.

Peter Fernandez 2K

The existence of lone pairs does not always indicate if a covalent bond will be polar, but a difference in electronegativities between the two atoms in the covalent bond can indicate if it is polar!

Peter Fernandez 2K

For determining if a bond is polar or nonpolar, it's important to think of difference in electronegativities. When two atoms are covalently bonded and have very different electronegativities (C-O for example) then the bond is polar. If the two atoms have similar electronegativities, like having two ...

Peter Fernandez 2K

Delta p is the change in momentum, which uses the units kg*m/s. Delta x is the change in position, which uses the units of m!

Peter Fernandez 2K

When I balance equations, I usually go for the element that exists either alone on both sides or the element that only shows up once on both sides. By balancing that element first, it's easier to balance the elements that show up twice or three times, etc.

Peter Fernandez 2K

I would do all the optional textbook problems, review Achieve, and study with friends by trying to teach them the concepts! If you're still struggling, I recommend going to the UA step-up sessions!

Peter Fernandez 2K

For the work functions, you'd use the equation E(photon) - Work Function = KE. You can manipulate this by adding work function to the other side and subtracting KE to solve for work function.

Peter Fernandez 2K

Kg is used instead of g because it is the standard SI unit for mass!

Peter Fernandez 2K

I personally prefer using 1.01 when significant digits aren't specified!

Peter Fernandez 2K

There's no guarantee that it will always be given, but if you use the Periodic Table Lavelle provides I'm sure you'll easily be able to use the masses in the table to add them up and get the molar mass of any molecule you'd need.

Peter Fernandez 2K

The decimal gets rid of the trailing zeros, therefore making it 3 significant figures instead of 1.

Peter Fernandez 2K

Molar mass is intensive since it is always the same regardless if the size of the sample changes. It is independent of the size of the sample.

Peter Fernandez 2K

Molar mass is intensive since it is always the same regardless if the size of the sample changes. It is independent of the size of the sample.

Peter Fernandez 2K

Since you want to substitute variables to solve for wavelength, you would need to use the equation C= λv by dividing lambda on both sides to get v = C/λ. Then, substitute v into E = hv to get E = hC/λ.

Peter Fernandez 2K

Hi! As far as I know, there is no place to view all the deadlines for the rest of the quarter, sorry!

Peter Fernandez 2K

The number of sig figs you use will always be determined by the number with the lowest sig figs in the calculation, so if it's 1, then your answer must use 1 sig fig.

Peter Fernandez 2K

This is really cool and helpful! It was really encouraging, thank you so much :)

Peter Fernandez 2K

I usually find which element is easiest to isolate and balance and work my way from there. If you want, you can write out each element on both sides to keep track of how many of each you have.

Peter Fernandez 2K

I think you do, as all Achieve homework is mandatory.

Peter Fernandez 2K

You're correct, you have immediate access to the textbook and will be charged week 3 on your bruinbill if I'm correct.

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